#ifndef _CRYPTO_H_
#define _CRYPTO_H_
/* Description: This function used to encrypto message in $plaintext, and put ciphertext into $ciphertext
* Return value: 0: Success <0: Failure
*/ 
extern int encrypt(char *plaintext, char *ciphertext, int size);
 
/* Description: This function used to decrypto message in $ciphertext, and put plaintext into $plaintext
* Return value: 0: Success <0: Failure 
*/ 
extern int decrypt(char *ciphertext, char *plaintext, int size); 
#endif /* ----- #ifndef _CRYPTO_H_ ----- */